Valve



Jan. 25, 1944. R. 1-. HEDFIELD VALVE Filed May 10; 1940 2 She ts-Sheet 1 R. T. HEDFIELD Jan. 25, 1944.

VALVE Filed May 101 1940 y 2 Sheets-Shegt 2 r IIIII Patented Jan. 25, 1944 UNITED STATES VALVE Reynold 1. Hedfibfi lihieagmlll -assignor to'las;

F. Marsh Corporation, chieaxegm a'eoepora- :tion of Illinois 2 Application May 111,-1940; Serial No.j33 ,1 5"

seams. (-01. are -e4)" This invention relates tov valves, valve assemblies and casings therefor,,and more-ipartlculany'te vent valves :for radiators and thelike ion.

walls being reinforced by suitable strengthening ribs arranged to impart an artistictandiat tractive design to the exteriorof the oasingiand at the same time materially reinforce-.thethin' walls thereof; 'Itis, of course; necessary that; valve casings of the-character-setforthiabove havesuificient strength and; zrigidity to withstandaccidental blows and shocks so; as to'tpr'e vent damage totheyalvemechanisnrwithin the casing and accordingly-valvecasingseonstruotedi in accordance; with" the present. invention: are preferablyprovided twith'heavyorthicksend wattswhich in ome -instancesmay be :aperturedizte receive suitable adjusting means; the thickness of the end -wall; heingagreatertthan therange of adjustment so that the adjusting meansi-is-at all-times retained withinjthe confines of the wall.

Metal such as aluminum, zinc; .tin,..and the like, particularly aluminum, which constitutes the preferred metal used in ,thecasin s ofuthe present invention, cannot readily be weldedaor'. soldered, and accordingl diificultiesareencountered in assembling such valve casings.onuthev valve mechanisms to beenclosedthereby It is; therefore, another object of this invention to provide a-casing which may readilybe so as sembled together witha method of assembly by virtue-of which the easingis accuratelyiposi tioned .and permanently secured, in-the desiredposition relative .to the valve mechanism.

A further object of the inventionis to pro-.- vide a vent valvehaving adjustable float means forcontrolling the-vent-and in'which the float means isv expansible for closing. the vent intesponse .to; predetermined temperature .mithlntthe valve chamber.

It is .alsoanobjeet torrovide a .valvaof 1 the character described in which thepositlon of the float withrespeot to the. vent may-accuratelybe adjusted before. complete assembly of .the valve and whereinthe adjusting means inaccessible after the .valve.hasheen'permanently assembled and sealed .for use,

The invention also provides a valve structure. in which'theifloatmay be adjusted-before complete assembly. or may be adjusted through .a. suitable opening after complete assembly and after which llatteradjustment the opening may permanently be-sealedi Itis alsoan objecttoprovide a. sectional valve body in which one-of the sections is providedwith a .vent openin'goand meansfor adjusting a fioat thereinrelativ'e to thevent opening and also'lnwhioh thefioat adjusting mechanism is inaccessiblewhen the'sections arevsecured toether andsealed toliorm a fioat ehamberhaving a single inlet adjacent one end and a vent opening adjacent the-other end.

A further object is the provision of avalve of the. chflactehdescribed having a sectional float-chamber .withia float therein for controlline; a ventirom said, chamber and an outerad'liisti'ng-v mean supported entirely by thelow'er float chambersection; also-in which afloat adjusting screw extends through. or is accessible through, an opening in the bottom-of the assembled-valve andmay be madev inaccessible by suitably sealing. the openingto condition the valvelfor r V v Eurther objects. .wiIlbe apparent from the sp o fl afion andtheapnendedclai'ms Fig. 1. ism-perspective .view -,ofone embodiment ofla Naive casing-ior-ming-a-part of this invention. I g I Fig; 2' is .an axial sectional elevation of a completelyassembledyalve.

an axial sectional view; oithe valve chamber and float mechanism and is taken on. a.

line substantially corresponding to line 3-3 of Fig. 2.

Fig. 4 is an enlarged view of the float adjusting device and illustrates the method of sealing the adjusting screw and the float chamber.

Fig. 5 is an axial sectional view similar to Fig. 2, but illustrates a slightly diiferent embodiment of adjusting mechanism.

Fig. 6 is a fragmentary sectional view taken on a line substantially corresponding to line 66 in Fig. 5.

Fig. '7 is a perspective view of the supporting means for the float adjusting screw.

Figs. 8 and 9 are side elevations of bottom inlet valves, partially in section, and illustrate-the method of securing casings of the type shown in Fig. 1 to bottom inlet valves.

Referring to the drawings in detail, the valve casing I illustrated in perspe'ctive'in Fig. 1 as comprising a preferred embodiment ofthe inof the ribs 4 terminate in an annular raised porl tion 5 formed on the upper surface of the end wall. In this embodiment of the invention, the ribs 4 are symmetrically arranged in four groups of three ribs each, the central rib of each group preferably being somewhat. wider than the outer 5 ribs. An artistic design is thus formed on the valve casing and the relationship of the ribs to the raised circular portion 5 of the end wall complates the design and at the same time the ribs and their distribution materially strengthen the thin side walls, which otherwise are of insufficient strength to resist the rough usage to which such casings are often subjected. In addition to its function of co-operating with the ribs to complete thedesign, the circular portion 5 forms a convenient surface upon which suitable a'dvertising or identification indicia may be located for co operation with a vent adjusting means which may be located in an opening 6 in the end wall 2 after the entirevalve isassembled.

- The opening or aperture 6 extends completely through-the end wall 2 centrally of the raised portion 5. It will be apparent from the drawings that the valve casing therein shown presents a very attractive appearance, and it has been found that a casing of this character,- having a' thick end wall for strength and relatively thin'side walls for economy of material and provided with longitudinal strengthening ribs, provides a highly ad'- vantageous construction, particularly when used in connection with valve mechanisms of'the type disclosed herein and which will be more fully described hereinafter. 4

Although it would probably be possible to form casings such as illustrated and described herein, by various casting, molding, and machine opera-' tions, such procedure would berelatively expensive, and these casings are; therefore, particularly designed for manufacture by an impact extrusion process. By means v of the impacting extrusion process, castings of this character may be formed very quickly and inexpensively and by a minimum of machining and finishing operations.

The manufacturing process involves the impact extrusion of suitable flowable metals in such'a fashion as to form the completed casing with a single impact, the strengthening and decorative ribs 4 being instantly extruded integrally with the side walls during the forming operation. Additional advantages of the impact extrusion process are found in the uniformity of the finished products, the high mechanical strength obtained clue to the fact that impact extruded aluminum is strain-hardened, and the low production costs involved. The casing illustrated is' particularly adapted for manufacture by this process.

Although the casings are not limited to use in .connection with the particular types of valve mechanisms shown, they are especially useful in connection therewith. Fig. 2 illustrates a preferredformofi valve mechanism enclosed in one of the casings shown in Fig. 1 after the casing has been extruded and subjected to certain mach- "ining operations in order to adapt it for use in thevmanner shown. These machining operations comprise the removal of the ribs 4 from the blank for ashort distance adjacent the open end of the casing so as to provide a thin end portion 1,

alsothe-provision of a'notch 8 in one side of the casing adjacent the open end thereof, the formation of a plurality of small apertures 9 in one side of the casin preferably along one of the ribs 4, and the formation of the heretofore mentioned aperture 6 in the end wall 2, the aperture 6 preferably being formed so as to provide an annular other as shown and which are permanently se-' cured together and sealed at H by any suitable means, preferably by soldering or any similar se-" curing-and sealing method. The upper memberl2 constitutes the vent section of the chamber ll andis provided with an axially positioned up-'- wardly extending vent nipple I5 having an axial 5 passage I B'therethrough and a transverse passage I7 communicating therewith and forming apair of lateral vent openings. The enlarged upperend of the axial passage is provided with an adjustingscrew [8 having an axial tip l8a adapted to control the size of the vent opening when the screw I8 is adjusted. The vent nipple I5 is pref erably inserted in an axial opening inthemember' l2 an'd i's soldered or brazed therein or secured in any other suitable leak-proof manner.

.: A' fsheet metal li'q'uid control cup 19 is supported in thechamber. II with its open end ex-' tending into the upper member I2 loosely or slidably fitting therein as shown in Figs. 2 and 3. A portion of the walls of the member 19 are 'indented or corrugated to provide passageways 2U (Fig. 3) to establish communication between the bottom of the valve'chamber H and the 'vent'outg let passage I69 The-lower cup shaped member- !3 of the chamber I I has its bottom-wall formed inwardly as, shown to provide a re-entrant portion 2| having an enlarged axial ope ning..there-" throughlto providejclea-rance for a downwardly.

extendingthreaded portion 22 of the liquid con-' trol 'cup [9 .afterthe parts are assembled and to enable the bottomof the cup to the lower chamber member: 13 is telescoped over the upper member I2, the liquid control cup l9:

rests on the upper surface of the reentr'ant por rest snugly on tion 21 so that these portions may later be sealed together. The cup I9 is provided with an axial adjusting screw 23 supporting a float 24, which latter may be of the usual type responsive to flotation and temperature changes to control the vent and is provided with an upwardly extending stem 25 adapted to close the vent passage l6 when the float 24 is raised by water entering the chamber II or when it is expanded by predetermined temperature within the valve.

The lower cup member 13 which Constitutes the base or inlet section of the valve chamber II is provided with a laterally extending spud 26 which may be threaded as shown to enable the device to be attached to a radiator or other part of a heating system. This spud 25 may be secured and sealed in the base l3 in any suitable means, preferably by means of an inner flange Zlhaving lugs 28 thereon adapted to enter suitable complementary openings in the wall of the an outturned retaining flange 36. A sheet metal member 3| is provided with a slot 32 to receive the end of the siphon whereby the siphon is loosely retained in position. The sheet metal member 3! is preferably soldered or otherwise secured to the spud flange 21.

In assembling the device, the float 24 is positioned in the upper cup shaped member l2 with the vent controlling stem 25 in position to control the vent opening in the usual manner. liquid control cup is is then inserted with the adjusting screw 23 against the bottom of the float and the member or base i3 of the chamber l I is telescoped over the upper portion I2 so that the end of the re-entrant portion 2| is in contact with the bottom wall of the cup H] with the adjusting screw 23 extending through the enlarged opening therein so that this screw is accessible for adjustment after the device is assembled but before being completely sealed for use. The cup shaped chamber members 52 and [3 may then be secured together and simultaneously sealed at M by soldering or any other suitable method. After the unit is assembled as described, the adjusting screw 23 is acces sible from the bottom of the unit for adjustment of thefio'at, although the screw is entirely confined within the general contour of the unit. The unit'may then be subjected to a predetermined temperature and an adjustment made for control of the vent in a desired manner, after which the adjusting screw may be locked andsealed simultaneously with the sealing of the joint between the bottom of the cup l9 and the re-entrant portion 2| by applying solder over the end of the screw 2s and the opening through which it extends as shown at 33. The solder 33 secures the parts together and the adjusting screw 23 is made normally inaccessible after the device is completely assembled and sealed, and the adjustment is, therefore, retained indefinitely. l

The previously described outer casing l of impact extruded material and constructed asiilustrated in Fig. l is arranged to telescope downwardly completely over the valve chamber as shown in Fig. 2 with the notch 8 providingclear ance .for the inlet spud 25. the upper edge of the notch 8 is accurately located so as to provide. a stop against thespudto limit the 'dow'n:

The

ward telescoping of the housing. The bottom of the base member I3 is preferably provided with an annular shoulder 34 to align with the bottom of the casing after it'is secured thereon.

-After the outer housing is fully telescoped over the chamber unit, the lower edges are rolled or crimped over the bottom edge of the lower cup section l3 to form a smooth rounded corner as shown at 35. This provides a completelyem closed doubleshell structure having no outwardly extending projections except the inlet spud 25 and the associated siphon'29.

As previously stated, the upper end of the outer casing I is provided with an axial opening 6 to receive the upper end of the vent adjusting screw I8, and this adjusting screw is preferably provided with a rectangular or irregularly shaped head 36 to be received within a similarly shaped opening 31 in an adjusting plug 38. The plug 38 is preferably mounted entirely within the opening 6 of the casing so that its outer surface forms a smooth continuation of the outer surface of the casing and is supported therein by means of a plate 39 secured to the end wall 2 of the casing by means of riveting lugs Mi. The plug 33 is retained in assembled relation with the casing by means of a resilient split ring M in an annular groove 42 in the plug. When the plug with the split ring assembled in.

the groove 42 is pushed inwardly into the casing; the resilient split ring engages the shoulder ID.

of the casing and the plug is thereby rotatably retained in position. The plug is provided with a slot 43 whereby it may easily be rotated forv adjusting the vent control screw 18 and the sup porting plate 39 is provided with an upwardly extending lug M which is adapted to be .engaged by a stop 55 on the plug to thereby limit. the rotation of the plug and the consequent adjustment of the vent over a predetermined range. The plug 38 and the annular ring sur face 5 of the casing may be provided with oooperating indicia to predetermine the vent con.- trol by the'proper setting of the plug.

As previously stated, the outer shell or enclosing casing l is provided with a series of small openings or perforations 9 which are preferably" arranged inv a vertical row substantially as shown in Figs. 1 and 2, whereby the perforations are at progressively increasing distances from the vent openings ll. Air or other fluid discharged from the vent openings ll expandsin the upper part of the outer casing, which, after assembly, forms a muiiler chamber at, and the fluid is accordingly exhausted at reduced velocity from the perforations or ports 9. Since these ports are arranged at progressively increasing distances from the vent openings, unequal velocities of flow eX- ist at the different ports, and the tendency of the exhaust fluid to produce audible sound is thus materially reduced. Furthermore, such soundas may be produced at the vent opening I! iseiiectively dissipated by the construction of the casing l and the arrangement of the ports 9 relative thereto.

The impact extrusion casing previously described is particularly adapted for use in the relationship disclosed. Furthermore, it isprefe rable to provide the casing with a relatively thick upper wall adjacent the vent opening, as this con struction, combined with the type of material used, augments the sound dissipating and eliminating characteristics of the mufiler chambe'r td and the exhaust ports 9, the nonresilient charac'-- ter of the material and the thick upper wall andreinforcing ribs tending to reduce the so-called sympathetic vibration of the casing.

Furthermore, the ports 9, by reason of their small diameters and their longitudinal arrangement and progressively increasing distances from the vent openings, tend to round off the sharp wave fronts of the sound waves initiated at the vent openings and thus further assist in providing a noiseless construction. Also, the particular type of casing provides an additional advantage in the thick upper wall in that sumcient adjusting space is provided within the confines of the wall itself so that the movable elements of the adjusting mechanism are positioned entirely within the contour of the casing and Within the confines of the thick upper wall in position for adjustment of the vent openings. Thus, unsightly projections from the valve casing are eliminated. l

The construction provides a large float chamber having plenty of space for air and water separation so as to minimize to a large degree float bobbing and spitting. The automatically controlling float may accurately be adjusted before or after complete assembly and a positive float H action and quick response to temperature are assured, so that'the vent is immediately closed when steam reaches the float chamber. Any venting rate from minimum to maximum is obtained by merely turning the plug 38 to a desired point in accordance with the indicia. An inexpensive, easily assembled, and easily adjusted double shell construction is provided in which air is vented into the muflier compartment between the shells where it expands and leaves noiselessly through the plurality of small discharge ports.

A baflle plate 41 may be mounted on the floats l so that the outer edges of the bafile extend over the passageways between the float supporting cup I9 and the upper member l2 and which are disclosed in the path of the fluid flowing through the corrugations. Thus, upon the occurrence of a sudden surge of high velocity flow of fluid through the corrugations, the impactof the fluid on the baffle 41 is effective to raise the float member 48 independently of the flotation and temperature conditions existing within the valve and thereby close the vent opening and prevent spitting of the valve.

The cup shaped float supporting member l9 surrounds the float element so as to form a float chamber of restricted capacity, and it will be ap parent that, upon the accumulation of liquid Within the member I9, the float will be operated by this liquid to close the vent opening. The accumulation of liquid in the cup member l9 may occur due to the deflecting action of the bailie 41, which tends to deflect entrained liquid flowing through the corrugations or passages so that this liquid accumulates in the cup I9.

The condensation of steam in the upper portion of the valve chamber II will also result in accumulation of liquid within the cup l9 and the baffle 41 is provided with a plurality of apertures 48 which permit the condensate to enter the cup member I9 from the upper end thereof. Provision of the restricted capacity float chamber formed by the cup I9 is highly eflectivein preventing bobbing of the float due to sudden changes in the liquid level within the valve chamber or due to surges.

The float supporting cup 19 is provided with a small aperture 49 adjacent the bottom thereof,

through which aperture liquid accumulated in the cup l9 may return to the lower portion of the valve chamber ll wherefrom it is discharged through the siphon 29. That portion of the cup l9 below the aperture 49 is at all times filled with liquid, and accordingly a very small additional amount of liquid will raise the float sufliciently to close the vent. opening. Thus, upon a sudden surge of the fluid flowing through the passages 20 of suflicient velocity to effect operation of the bailie 41 so as to close the vent opening, there may be a considerable quantity of entrained liquid deflected into the cup 19, and the consequent rise in the level of the liquid within the cup will serve to hold the vent closed for a short interval following such a high velocity surge. Whenever the liquid level in the valve chamber I l rises above the aperture 49, the liquid flows into the cup l9 so as to raise the float 24 and effect closure of the vent opening if the vent is not already closed due to temperature conditions existing within the valve chamber.

The capacity of the aperture 49 is considerably less than the drainage capacity of the siphon 29, and, accordingly, when conditions are such that liquid is being withdrawn from the valve chamber through the siphon tube at a greater rate than it is being accumulated in the chamber, so that the liquid level falls below the aperture 49, liquid drains from the cup I9 at a rate which is less than the rate of discharge of liquid from the valve chamber. Therefore, sufflcient liquid will be retained in the cup I9 and slowly drained therefrom to maintain the vent closed until substantially all of the liquid within the chamber H has been withdrawn through the siphon. This insures that, when the liquid level within the valve chamber H has fallen approximately to that level at which the vent would open if the cup l9 were not provided, sudden changes in liquid level will noteffect bobbing of the float, since suflicient liquid is retained in the cup l9 to hold the float firmly in vent closing position.

The embodiment illustrated in Figs. 5, 6, and 7 comprises a valve chamber Ila which is very similar to that previously described and is formed of two cup-shaped sheet metal members 50 and 5| arranged to telescope each other, as shown, and which are permanently secured together and sealed at 52, preferably by soldering or other suitable method. The upper member 50 constitutes the vent section and is provided with an axially positioned upwardly extending nipple 53 having an axial passage 54 therethrough and lateral vent openings 55 communicating there- I with. The upper end of the axial passage is threaded and provided with an adjustingscrew 56 for controlling the size of the vent openings. The lower cup member or base 5| is provided with a spud 26a having a siphon 29a supported therein, and this spud and siphon may be similar to that previously described and may be secured in the base in the same manner. The bottom of the base 5| is preferably provided with an annular shoulder 51 and an axial re-entrant depression 58 having an opening 59 therethrough of a size adapted to receive a screw driver for adjusting the valve during test in a manner which will later be described. After the adjustment has been made, the opening 59 is closed by meansof a plug 60 which may be secured in the opening and properly sealed by means of solder or the like, as illustrated at El.

' A valve supporting strap or yoke 62 is formed substantially as illustrated in Fig. 7 and provided with a raised central portion 63 and upwardly extending arms 64. The arms 64 are preferably arcuate to conform with the contour of the inner surface of the base whereby the yoke fits snugly therein and may be retained in position by friction against the side walls. During assembly, the yoke is first inserted in the base and the upper member 50 thentelescoped therein until it rests on the ends of the arms 64 of the in position between the bottom of the base 5| :and the lower edge of the upper member 50.

The central raised portion of the yoke 62 is provided with an axial threaded opening 65to receive an adjustingscrew 66 on which the float 24a is supported, the float, of course, being pro'- vided with the usual stem 25a, adapted to'control the vent opening. The float 24a is of the same type as previously described and is expansible in response to predetermined temperature.

The construction disclosed provides a transversely extending raised float support or yoke having a float adjusting screw therein in alignment with the base opening 59,- and the entire support is mounted in the lower base and retained therein by the upper member 56. Therefore, after this inner mechanism is assembled, the sub-assembly may be tested and the screw 66 adjusted to provide apredetermined vent con- 7 trol by the float 24a, after which test and adjustment the plug 60 may be inserted and the opening sealed as previously described, whereby the adjusting screw is normally inaccessible after complete assembly and sealing.

The outer casing la of impact extruded metal, which may be substantially identical with the eas- -ing I previously described, may then be telescoped downwardly completely over the valve chamber Ha, as shown, and positioned thereon and secured in the same manner as previously described by rolling or crimping the edges a over the bottom edge of the base 5|, as shown. This provides a completely enclosed double shell structure having no outwardly extending projection except the inlet spud 26a and the associated siphon 29a.

The upper end of the vent adjusting screw 56 is positioned within the opening 6a in the thick base 2a of the outer casing. A washer 61 is provided under the head of the screw to close the opening 60. and a spring 68 retains the screw in any adjusted position. The head of the screw 56 is provided with a pointer portion 69 which co-operates with suitable indicia on the upper end of the casing to predetermine the vent adjustment. The thick end wall 2a, of the casing enables the screw head to be positioned at all times within the outer contour of the casing. This double shell valve and the type of casing used provides all of the desirable structural and sound eliminating characteristics which have previously been described in connection with the other embodiments disclosed herein.

The valve structures thus far referred to are provided with laterally extending spuds arranged to co-operate with a suitable slot or notch in the outer casing so as to properly position the casing. The same impact extruded casing may also be applied to valves known as straight valves, wherein the inlet spud extends axially from the lower end wall of the valve chamber. Such a construction is illustrated in Figs. 8 and 9, wherein a tubular valve chamber, similar to those previously described, is provided, the valve chamber iii) 'in this construction comprising an upper cup shaped-member l0 and a lower cup shaped member H, the bottom'wall of the latter member being shaped'as shown to provide an axially ex- ...tending inlet spud 12. Since the inlet spud 12 in this form of valve may interfere with the float supportingand adjusting structures shown in Figs. 2 to 7, inclusive, I prefer in this type of valve to use the construction disclosed and claimed inthe above referred to U. S. Patent No.

12,287,075. In order toposition the outer valve casing lb shown in Fig. 1, except that the notch 8 is omitted, is telescoped over the valve chamber, the

flange 13 engages the-lower end of the casing lb so as initially to position the casing in predetermined relation to the valve mechanism. Permanent locking of the :casing in this position may then be accomplished simply by spinning or pressvingthe lower edge of the casing side wall inwardly: so as tightly to engage a suitable rounded shoulder M on the lower end of the base member El, and by then spinningor pressing upwardly the flange '13- so as to-snugly overlap the end of the casing 64; as shown'in Fig. 9, whereby thecas- "ing la is firmly locked in position with respect to the valve mechanism. It will be apparent that in all of the embodiments shown the type of casing used and the method of securing the outer casing to the valve mechanism results in a smooth finished appearance, since no extending rivets or locking members are necessary.

It is intended, of course, that the invention should not be limited to the specific embodiment or embodiments disclosed herein, since many modifications may be made, and it is contemplated, therefore, by the appended claims to cover any such modifications as fall within the true spirit and scope of this invention.

Having thus described this invention, what is claimed and desired to be secured by Letters Patent is:

1. In combination, an air valve mechanism including a substantially tubular valve chamber having adjustment means extending axially from one end and an inlet stud projecting from a side of said chamber adjacent the other end, an outer housing comprising an aluminum shell telescoped over said chamber having a notch for receiving said projecting stud, said aluminum shell having a thick end wall apertured to receive said adjustment means whereby said adjustment means is accessible for manipulation, engagement of said stud with the end of said notch being eifective initially to position said shell on said chamber so that said adjustment means is contained within the aperture in said thick end wall throughout its range of adjustment and so that the open end of said shell extends beyond said other end of said valve chamber, the extending end of said shell, upon being pressed inwardly tightly to engage said other end of said valve chamber, permanently securing said outer housing'in said initially determined position.

2. A vent valve comprising a valve chamber having a bottom inlet and a top vent, a condition-responsive element in said chamber in vent controlling relationship, a bridge frictionally secured in said chamber between the bottom wall and said element, said bridge comprising spaced apart arms engaging'opposed side walls of said chamber and a portion extending transversely of said arms in a plane intermediate the upper and lower ends of said arms, and means on said transversely extending portion of said bridge for adjusting the controlling relationship of said element to said vent.

3. A vent valve comprising a valve chamber having a bottom inlet and a top vent, a bridge extending upwardly from the bottom wall of said chamber comprising a transverse portion supported On opposed anns, said arms extending downwardly from said bridge to said bottom wall and then upwardly to a point beyond said transverse portion, whereby said transverse portion .lies in a plane intermediate the upper and lower ends of said arms, an axial screw supported on said transverse portion of said bridge, and a temperature responsive float valve on said screw in adjustable vent controlling relationship to said vent.

4. A vent valve comprising an upper section and a lower section sealed together to form a valve chamber having a vent in the upper section and an inlet in the lower section, a temperature responsive float valve in said chamber, a bridge in said lower section having a transverse portion supported on opposed arms in a plane intermedi ate the ends of said arms, said arms extending along the walls of said lower section whereby said bridge is frictionally retained against rotation in said lower section by engagement with the walls thereof, the lower ends of said arms engaging the bottom wall of said lower section and the mined position.

upper ends of said arms being positioned to engage the lower edge of said upper section whereby said bridge is retained against axial movement in said lower section, and means on said transverse portion of said bridge for adjusting the controlling relationship of said float valve to said vent. 5; -In combination, air valve mechanism including a substantially tubular valve chamber having adjustment means extending axially from one end and a projection extending outwardly from a side of said chamber adjacent the other end, an outer housing telescoped over said chamber having a notch for receiving said projection, said outer housing having a thick end wall apertured to receive said adjustment meanswhereby said adjustment means is accessible for manipulation, engagement of said projection with the end of said notch being effective initially to position said housing on said chamber so that said adjustment means is contained within the aperture in said thick end wall throughout its range of adjustment and so that the open end of said housing extends beyond said other end of said valve chamber, the extending end of said housing upon being pressed inwardly tightly to engage said other end of said valve chamber permanently securingsaid outer housing in said initially deter- REYNOLD T. HEDFIELD. 

